Side effects are rare but you may experience:
- Blocked nose
- Facial flushing
- Increased sweating
- Abdominal pain
It’s a very rare side effect, but if you have a prolonged erection for more than 4 hours then you need to contact your doctor immediately.
Nitrates interact very adversely with all phosphodiesterase type 5 inhibitors like Spedra, Viagra, Cialis, Levitra and sildenafil. They can cause a FATAL lowering of blood pressure and should NEVER be used together.
Nitrates include medications like GTN spray, isosorbide mononitrate and nicorandil for angina. Also, the recreational drugs called "poppers" should be avoided.